How do I read a file from todays date and previous date using .CSV file

Question

Dipesh Ramesh 2014-7-21

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/142793-how-do-i-read-a-file-from-todays-date-and-previous-date-using-csv-file

评论： Geoff Hayes 2014-7-22

I am new to Matlab, I was wondering how do i read 1st row and 2nd row from a .CSV file. This is what I have done:

      str = urlread('http://ichart.yahoo.com/table.csv?s=AMZN&a=0&b=1&c=2014&d=0&e=31&n=2014&g=d&ignore=.csv');
      i = 0;
       [dates,o,h,l,c] = dataread('string',str,'%s%f%f%f%f%*f%*f','delimiter',',','headerlines',1);
       dates = datenum(dates);
       firstDate = dates(2)
       secondDate = firstDate(3)
      if () 
          i = i+1;
      end

At the moment I can get the first row and second row, but what I need is the final row and final row +1. So from backward compare two rows at the time. Check if open price number in first row is grater than open price number from the second row (bottom up) if yes +1 and save file. For example from the above file the last few files looks like this:

 Date,Open,High,Low,Close,Volume,Adj Close   
2014-01-17,394.26,403.49,393.66,399.61,4505100,399.61
2014-01-16,393.68,399.29,389.41,395.80,2601200,395.80
2014-01-15,398.94,399.31,392.53,395.87,2678300,395.87
2014-01-14,392.13,398.63,391.29,397.54,2340100,397.54
2014-01-13,397.98,399.78,388.45,390.98,2844900,390.98
2014-01-10,402.53,403.76,393.80,397.66,2679500,397.66
2014-01-09,403.71,406.89,398.44,401.01,2103000,401.01
2014-01-08,398.47,403.00,396.04,401.92,2316500,401.92
2014-01-07,395.04,398.47,394.29,398.03,1916000,398.03
2014-01-06,395.85,397.00,388.42,393.63,3170600,393.63
2014-01-03,398.29,402.71,396.22,396.44,2210200,396.44
2014-01-02,398.80,399.36,394.02,397.97,2137800,397.97    
So take 1st and 2nd lines below the file e.g. 
  2014-01-03,398.29,402.71,396.22,396.44,2210200,396.44
  2014-01-02,398.80,399.36,394.02,397.97,2137800,397.97

Now compare if 398.80>398.29 if yes +1 in file. Once this is done go on to 2nd and 3rd line e.g.:

2014-01-06,395.85,397.00,388.42,393.63,3170600,393.63
2014-01-03,398.29,402.71,396.22,396.44,2210200,396.44

Now compare if 398.29>395.85 if yes +1 in the file so (2) etc.. do it till the first file in the list.

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Answer 1

Geoff Hayes 2014-7-21

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/142793-how-do-i-read-a-file-from-todays-date-and-previous-date-using-csv-file#answer_145862

在 MATLAB Online 中打开

If you want to start from the end of the list, comparing the last two lines, the second and third last, etc., then use a for loop and just iterate backwards

 [dates,o,h,l,c] = dataread('string',str,'%s%f%f%f%f%*f%*f','delimiter',',','headerlines',1);
 dates = datenum(dates);
 numElems = length(dates);
 % iterate from last element in list to second element, comparing two at a time
 for k=numElems:-1:2
   % compare the two open price numbers
   if o(k)>o(k-1)
       % do something
   end
 end

The above code will allow you to do the correct comparisons; the do something comment refers to your if yes +1 in file (which I'm a little unclear on).